1. Field of the Invention
This invention relates generally to a handle for holding and manipulating drafting instruments such as triangles, templates, and the like.
2. Description of the Prior Art
A common problem with known handles of conventional type is that they do not provide a proper grip without interfering with the normal use of the drafting instrument.
There have been devices devised to hold drafting instruments, but oftentimes these still are far from effective. Similarly, known structures for holding drafting instruments are difficult to grip, expensive to manufacture, and in general leave much to be desired.
Existing prior patents which may be pertient to this invention are as follows:
______________________________________ R. B. Ware 1,145,531 July 6, 1915 J. R. Hageman 3,061,933 Nov. 6, 1962 S. S. Coe 4,194,293 Mar. 25, 1980 ______________________________________
These patents differ from the present invention as follows: The handle by Ware does not provide for a proper grip because it cannot be grasped with equal ease from all angles. It is not suited to the usual drafting environment because when the triangle is slid across the surface of a drawing, eraser residue can rapidly collect in the open slot and spring, thus impairing the operation of the handle. The handle would likely be costly to produce because it uses several moving parts requiring close dimensional tolerances and factory assembly. The triangle also requires special machining for the handle to function in the desired manner.
The handle by Hageman also does not provide the proper grip because it cannot be grasped with equal ease from all angles. Furthermore, it is not attached to the triangle with sufficient firmness and the resultant side-to-side wobble would reduce its usefulness as a handle. The durability of the handle is questionable, since the very small contact area of the bearing surfaces 25 and 16 would be subject to rapid wear and breakage. Obviously, the triangle requires special machining.
The lettering triangle of Coe does not specifically address the problem of handling triangles. Although the triangle is equipped with a knob assembly 30, neither the knob assembly nor the triangle appear to be reversible. The durability of the knob assembly is questionable due to the small contact area of the hole 15 and the threaded post 16. Of course, the triangle requires special machining.
Although certain features of the referenced inventions are similar to the present invention, none of the cited devices meets all of the requirements for a good handle for a drafting instrument in the manner of the present invention.